A support structure is usually used in horizontal (floor and slab) and vertical (wall, stack and pillar) formworks which is formed by braces on which formwork girders having a web of wood or made completely of wood are placed transversely, on which girders the formwork boards are nailed for the subsequent pouring of concrete.
The braces are normally usually U-shaped girders which are opposite at their base, whereas the formwork girders are double T-shaped girders made integrally of wood or metal girders with their upper base lightened, defining a channel in which a core of wood is housed.
Devices such as those described in patents DE 32 31 220 and DE 100 33 425 are used for the connection between the brace and the formwork girder.
Patent DE 32 31 220 describes an anchoring device consisting of two arms in a parallel arrangement provided at one of their ends with hooks intended to be coupled in one of the flanges of the brace and at their other end they have boreholes for the passage of corresponding parallel flanges of a U-shaped structure, the transverse branch of which is coupled below the other flange of the brace.
The arms have flat expansions resting on the base of the formwork girders. To achieve the connection between braces and formwork girders the rods are finished in respective threaded studs in which nuts are screwed, which nuts push the arms on the base of the formwork girders, establishing in turn the anchoring of the U-shaped structure on the brace.
Patent DE 100 33 425 in turn also relates to an anchoring device consisting of an arm coupled on the flange of the brace by means of a hook and resting on the formwork girder by means of a flat expansion, also having a rod which is doubly bent at one end to embrace the flange of the brace and the formwork girder, and which terminates at its other end in a stud which is introduced in a borehole defined in the arm to which it is fixed by means of a nut, establishing the anchoring position.
Utility model ES 1 061 027 belonging to the same proprietor of the present invention proposes a connecting device incorporating respective arms provided with hooks at one of their ends for their coupling to one of the flanges of the brace, and at their other end they have flat extensions resting on the base of the formwork girder. The connecting device additionally incorporates rods, one of the ends of which is housed in respective tubular portions provided in the arms. These rods extend, after respective bends, in transverse branches embracing another opposite flange of the brace and meeting in a centered nut in which a screw is screwed, the tip of which impinges against this flange of the brace, thus establishing the fixing of the connecting device.
In this case, the tightening in the connection is achieved by means of the screw acting directly against the brace. However, the pressure of the screw against the brace determines that a spring effect which can tend to loosen the connection occurs in the rod forming the closure, this circumstance is especially problematic in the case of girders useful for raising the formwork once it has been assembled, in which the connection must be very solid.